Dear Maintainer, after updating debian stable 10 to 11, reimported my raid1 lvm VG (data) and caching it with a raid1 SSD pool, I got the same problem of missing binary /usr/sbin/cache_check during booting process (that fail by being enable to mount the caching VG). Installing the thin- provisioning-tools package has solved the problem. As far as I know, nothing in the manual of lvmcache(7) mentions this problem and dependency! Best regards and thanks again for the great job on Debian!